Golden Lion Tamarin
You think finding books about Saki Monkeys was tough? Huh! Try to find something about the golden lion tamarin.
The golden lion tamarin - Leontopithecus rosalia - to eggheads - is small primate living in the rain forests of Brazil. And we mean small. Adults may hit 1⅓ pounds, if they're hefty. Their classification by the International Union for Conservation of Nature (IUCN) bounces from Endangered to Critcially Endangered.
Today's there's are over 1000 individuals in the wild and things have gotten a bit better. In the early 1960's, some zoologists thought they were on the road to extinction as in some of their traditional habitats they had vanished completely.
"Leontopithecus rosalia", The IUCN Redlist of Endangered Species, http://www.iucnredlist.org/details/11506/0